Parallel digging, mining and filling operation coal mining method for controlling overlaying strata fracture and surface subsidence

ABSTRACT

Disclosed is a parallel digging, mining and filling operation coal mining method, in which a stope haulage roadway, stope branch roadways, and two-winged adits are arranged in a stope. The stope haulage roadway and the stope branch roadways serve as haulage passages, and coal mining work is carried out in the two-winged adits. All two-winged adits are mined sequentially and filled timely, and coal mass that has not been mined or two-winged adits that have been filled always exist at the two sides of the two-winged adit that are being mined, to support and control the roof. The two-winged adits can be mined without support or with less supports by controlling the length of the two-winged adits and the number of two-winged adits filled in one time, whereupon pillar-free mining can be realized.

FIELD OF THE INVENTION

The present invention relates to a coal mining method, belongs to the field of coal mining technology, and particularly relates to a parallel digging, mining arid filling operation coal mining method for controlling overlaying strata fracture and surface subsidence.

BACKGROUND OF THE INVENTION

Water-preserved mining refers to mining by a reasonable coal mining method and process, so as to ensure the mining disturbance will not cause damage to the water-bearing structure in the water bearing strata; or ensure the water level in the water bearing strata can recover within a certain time period though the water-bearing structure is damaged to some degree and some water loss occurs; or ensure the normal water supply will not be affected and at least the water supply can meet the demand of the ground ecosystem for water resource even though the underground water level can't recover to the original level.

Existing water-preserved mining techniques have a poor mining ratio, or can't attain a good water preservation effect, or don't have high recovery efficiency owing to the filling method. It is desirable to develop a coal mining method, which can realize quick, safe, and efficient coal mining while preserving water resources.

In addition, there is a large quantity of coal in “three unders” (under constructions, railroads, and water bodies) in China. According to the result of preliminary statistics performed in state-owned major coal mines, the total quantity of such coal is as high as 13.79 billion tons. As the technical level of coal mining is improved, to release the coal under constructions, railroads, and water bodies, techniques for mining the coal under constructions, railroads, and water bodies have been developed greatly. Presently, commonly used methods for controlling surface subsidence mainly include: coordinated mining, partial mining, grouting into separated strata in overburden, and mining with filling, etc. Coordinated mining utilizes the counter balancing among surface deformations resulted from simultaneous mining at multiple working faces to attain the purpose of reducing surface deformation, but it involves simultaneous mining at multiple working faces and is constrained by the layout of protected objects on the ground surface; therefore, it has severe impacts on the exploitation design and has limited applicability. Partial mining controls overlaying strata movement and surface subsidence by mining coal partially and reserving permanent coal pillars in certain width, and mainly includes Wongawilli mining, board and pillar mining, strip mining, limited thickness mining, knife mining, and roadway mining, etc. Though these methods can control surface subsidence to some degree, their mining ratios are not high, usually about 50%. Grouting into separated strata in overburden utilizes bore grouting to fill the space of separated strata between upper hard strata and lower soft strata, to attain the purpose of controlling the overlying bed subsidence above the hard strata and the surface subsidence; with that method, the surface subsidence reduction ratio is usually not higher than 40%. Compared with other methods for controlling surface subsidence, mining with filling is the most effective method for controlling surface subsidence at present, and the gob can be filled partially or fully. Depending on the layout of working face, the filling method can be gob filling along long-wall working face, strip filling, or roadway filling, etc. The problems existing in these methods mainly include: difficulties in coordination between coal mining and filling, complex filling system, large filling space, and long filling time, etc.

CONTENTS OF THE INVENTION

Technical problem: To overcome the drawbacks in the prior art, the present invention provides a parallel digging, mining and filling operation coal mining method for controlling overlaying strata fracture and surface subsidence, which is simple, can attain a high coal mining ratio, achieves a good surface subsidence control effect, and safely and efficiently controls overlaying strata fracture and surface subsidence. Technical solution: The parallel digging, mining and filling operation coal mining method for controlling overlaying strata fracture and surface subsidence provided in the present invention comprises the following steps:

-   -   a. arranging a stope haulage roadway I along the edge part or         middle part of a stope, and digging a stope branch roadway I         perpendicularly or obliquely to the stope haulage roadway I;     -   b. performing multiple two-winged adit mining in the coal mass         in the stope branch roadway I from inner side to outer side,         wherein, each two-winged adit mining and the corresponding         section of the stope branch roadway I is referred to as a stage;     -   c. performing an alternate two-winged adit mining in the next         stage at an interval equal to the width of a two-winged mining         adit along the stope branch roadway I, whenever the two-winged         adit mining in each stage is completed;     -   d. building sealing walls in the stope branch roadway I and         filling the two-winged adits and the corresponding sections of         the stope branch roadway I, after the multiple stages two-winged         adit mining is completed;     -   e. repeating steps b and c to continue the two-winged adit         mining in the stope branch roadway I, while executing the steps         d;     -   f. repeating the steps b, c, d, and e, till all two-winged adits         in the stope branch roadway I have been mined and filled;     -   g. digging a next stope branch roadway I parallel to the stope         branch roadway I at one side of the stope branch roadway I,         while mining and filling the two-winged adits in the stope         branch roadway I;     -   h. repeating the steps b, c, d, e, and f, till the next stope         branch roadway I and all two-winged adits therein have been         mined and filled;     -   i. repeating the steps b, c, d, e, f, and g, till all stope         branch roadways I and all two-winged adits therein at one side         of the stope haulage roadway I have been mined and filled;     -   j. digging a stope haulage roadway II on the other side of the         stope and digging a stope branch roadway II at one side of the         stope haulage roadway II, while mining and filling the stope         branch roadway I and the two-winged adits at one side of the         stope haulage roadway I, wherein, the stope branch roadway II is         located between two adjacent stope branch roadway I;     -   k. performing two-winged adits mining and filling in the stope         branch roadway II with the method described in the step b, c, d,         e, f, and g, till the coal resource in the entire stope has been         mined and filled.

The included angle α between the direction perpendicular to stope branch roadway and the adit is determined according to the requirement of the working angle of the coal mining equipment; the width of each two-winged adit is equal to the working width of the coal mining equipment; the distance L between adjacent stope branch roadways at the same side of the stope haulage roadway is determined with a formula L≈L₁+2L₂ ^(cosα), where, L₁ is the width of a stope branch roadway, and L₂ is the length of an adit.

Beneficial effects: In the present invention, stope branch roadways and two-winged adits are arranged, the two-winged adit and the corresponding section of the stope branch roadway are referred to as a stage, sealing walls are built in the stope branch roadway after multiple stages of mining is completed, and the two-winged adits are filled uniformly, to minimize the quantity of the sealing walls. The stope branch roadways are used as main haulage passages, and the coal mining work is carried out in the two-winged adits; the two-winged adits are filled timely, and two-winged adits that have not been mined or have been filled are utilized as roof supports, and the length of two-winged adits is controlled to eliminate the requirement for supporting; after the filling mass meets the strength requirement, the two-winged adits that have not been mined in the reserved coal pillars are mined with the same method, so that the coal is replaced by the filling mass. The coal mining method provided in the present invention overcomes the drawbacks in the existing coal mining method for mining the coal under constructions, railroads, and water bodies, such as low recovery ratio, difficulties in coordination between mining and filling, and complex production system, etc., realizes safe and efficient recovery of the coal under constructions, railroads, and water bodies while preserving the water resources, and can effectively control overlaying strata fractures and surface subsidence. The method enables synchronous and coordinated coal mining and filling, attains a high recovery ratio, achieves a good surface subsidence control effect, and realizes safe and efficient water-preserved coal mining through parallel digging, mining and filling operation while effectively controlling overlaying strata fractures and surface subsidence. The method is simple, can realize a high coal recovery ratio and a good surface subsidence control effect, and has wide practicability.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of first stage mining along the first stope branch roadway I at one side of the stope haulage roadway I (1) in the present invention;

FIG. 2 is a schematic diagram of second stage mining along the first stope branch roadway I at one side of the stope haulage roadway I (1) in the present invention;

FIG. 3 is a schematic diagram of third stage mining along the first stope branch roadway I at one side of the stope haulage roadway I (1) in the present invention;

FIG. 4 is a schematic diagram of filling for the first time in the first stope branch roadway I at one side of the stope haulage roadway I (1) in the present invention;

FIG. 5 is a schematic diagram of filling for the second time in the first stope branch roadway I at one side of the stope haulage roadway I (1) in the present invention;

FIG. 6 is a schematic diagram after the first stope branch roadway I at one side of the stope haulage roadway I (1) is filled in the present invention;

FIG. 7 is a schematic diagram after the second stope branch roadway I at one side of the stope haulage roadway I (1) is filled in the present invention;

FIG. 8 is a schematic diagram after the first stope branch roadway II at one side of the stope haulage roadway II (7) is dug in the present invention;

FIG. 9 is a schematic diagram after all stope branch roadways I at one side of the stope haulage roadway I (1) are filled in the present invention;

FIG. 10 is a schematic diagram after the second stage mining along the first stope branch roadway II at one side of the stope haulage roadway II (7) is completed in the present invention;

FIG. 11 is a schematic diagram after the third stage mining along the first stope branch roadway II at one side of the stope haulage roadway II (7) is completed in the present invention;

FIG. 12 is a schematic diagram after the filling for the first time in the first stope branch roadway II at one side of the stope haulage roadway II (7) is completed in the present invention;

FIG. 13 is a schematic diagram after the filling for the second time in the first stope branch roadway II at one side of the stope haulage roadway II (7) is completed in the present invention;

FIG. 14 is a schematic diagram after the first stope branch roadway II at one side of the stope haulage roadway II (7) is filled in the present invention;

FIG. 15 is a schematic diagram after the working face is mined and filled in the present invention;

FIG. 16 is a schematic diagram of the method provided in the present invention.

In the figures: 1, 6—stope haulage roadway; 2, 7—stope branch roadway; 3—two-winged adit; 4—sealing wall; 5—filling mass; 8—triangular coal.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereunder the present invention will be further detailed in an embodiment, with reference to the accompanying drawings. The parallel digging, mining and filling operation coal mining method for controlling overlaying strata fracture and surface subsidence provided in the present invention includes the following steps:

-   -   a. as shown in FIG. 1, a stope haulage roadway I 1 is arranged         along the edge part of a stope, and a stope branch roadway I 2         is dug perpendicularly or obliquely to the stope haulage roadway         I 1; or, a stope haulage roadway I 1 can be arranged in the         middle of the stope directly, and a stope branch roadway I 2 is         arrange at each side of the stope haulage roadway I 1.     -   b. then, performing multiple two-winged adits mining in the coal         mass along the stope branch roadway I 2 from inner side to outer         side; the included angle α between the direction perpendicular         to stope branch roadway I 2 and the two-winged adit 3 shall meet         the requirement of turning of the coal mining equipment during         operation; the smaller the angle, the less the triangular coal 8         in the schematic diagram will be, and the higher the recovery         ratio will be. Each two-winged adit 3 and the corresponding         section of the stope branch roadway I 2 is referred to as a         stage, and the width of each two-winged adit is equal to the         working width of the coal mining equipment; a next stage         two-winged adit 3 at an interval equal to the width of a         two-winged adit 3 is mined along the stope branch roadway I 2,         whenever the two-winged adit 3 mining in each stage is         completed, as shown in FIGS. 2˜3. The width and depth of the         adit 3 are determined according to the geological conditions of         the coal seam. The width and depth of the two-winged adit 3 can         be increased if the roof is stable. If the geologic conditions         of the stope branch roadway I 2 are poor, the roadway roof in         the triangular area of the two-winged adit 3 (i.e., the         intersection point between the two-winged adit 3 and the stope         branch roadway I 2) can be supported with crawler movable         supports or the like.     -   c. sealing walls 4 are built up in the stope branch roadway I 2         and the two-winged adits 3 that have been mined and the         corresponding sections of the stope branch roadway I 2 are         filled, after multiple stages two-winged adits 3 mining are         completed; the specific number of stages can be determined         according to the geologic conditions of coal seam; if the         geologic conditions of coal seam are good, more stages can be         used; otherwise less stages can be used; especially, the number         of stages should be determined according to the roof conditions,         to ensure that roadway wall rocks will not have severe         deformation, i.e., there is no severe roof collapse, and the         deformation of the sides is within a reasonable range. In the         schematic diagrams, 3 stages are shown. Sealing walls 5 are         built up in the stope branch roadway 2, and the two-winged         mining adit 3 that have been mined in steps b and c and the         corresponding sections of the stope branch roadway 2 are filled,         as shown in FIG. 4.     -   d. the steps b and c are repeated to continue two-winged mining         adits 3 mining in the stope branch roadway I 2, while the steps         d is executed.     -   e. a next stope branch roadway I 2 parallel to the stope branch         roadway I 2 is dug at one side of the stope branch roadway I 2,         while the two-winged mining adits 3 in the stope branch roadway         12 are mined and filled, as shown in FIG. 5.     -   f. the steps b, c, d, and e are repeated, till all two-winged         mining adits 3 in the stope branch roadway I 2 have been mined         and filled, as shown in FIG. 6.     -   g. the steps b, c, d, e, and f are repeated, till the next stope         branch roadway I 2 and all two-winged mining adits 3 therein         have been mined and filled, as shown in FIG. 7.     -   h. a stope haulage roadway II 2 is dug on the other side of the         stope, and a stope branch roadway II 7 is dug at one side of the         stope haulage roadway II 6, while the stope branch roadway I 2         and the two-winged adits 3 at one side of the stope haulage         roadway I 1 are mined and filled, wherein, the stope branch         roadway II 7 is located between two adjacent stope branch         roadway I 2, as shown in FIG. 8.     -   i. the steps b, c, d, e, f, and g are repeated, till all stope         branch roadways I 2 and all two-winged adits 3 therein at one         side of the stope haulage roadway I 1 have been mined and         filled, as shown in FIG. 9; the distance L between adjacent         stope branch roadways at the same side of the stope haulage         roadway is determined with a formula L≈L₁+2L₂ ^(cosα), as shown         in FIG. 16, where, L₁ is the width of a stope branch roadway, L₂         is the length of an adit, and a is the included angle between         the direction perpendicular to stope branch roadway 2 and adit.     -   j. the two-winged adits 3 in the stope branch roadway II 7 are         mined and filled with the method described in the steps b, c, d,         e, f, and g, till all coal resource in the first stope branch         roadway II 7 at one side of the stope haulage roadway II 6 has         been mined out and filled, as shown in FIGS. 10˜14.     -   k. the above steps are repeated, till the remaining two-winged         adits 3 at one side of the stope haulage roadway II 6 are mined,         as shown in FIG. 15. 

1. A coal mining method for controlling overlaying strata fracture and surface subsidence, comprising the following steps: a. arranging a stope haulage roadway along an edge part or middle part of a stope, and digging a stope branch roadway perpendicularly or obliquely to the stope haulage roadway; b. performing multiple two-winged adits mining in a coal mass in the stope branch roadway from inner side to outer side, wherein, each two-winged adit and the corresponding section of the stope branch roadway is referred to as a stage; c. performing next stage two-winged adit mining at an interval equal to a width of a two-winged adit along the stope branch roadway, whenever each stage two-winged mining adit mining is completed; d. building up sealing walls in the stope branch roadway and filling the two-winged adits that have been mined and the corresponding sections of the stope branch roadway, after multiple stages two-winged adits mining is completed; e. repeating steps b and c to continue two-winged adits mining in the stope branch roadway, while executing step the steps d; f. repeating the steps b, c, d, and e, until all two-winged adits in the stope branch roadway have been mined and filled; g. digging a next stope branch roadway parallel to the stope branch roadway at one side of the stope branch roadway, while mining and filling the two-winged adits in the stope branch roadway; h. repeating the steps b, c, d, e, and f, until the next stope branch roadway and all two-winged mining adits in it have been mined and filled; i. repeating the steps b, c, d, e, f, and g, until all stope branch roadways and all two-winged adits therein at one side of the stope haulage roadway have been mined and filled; j. digging a stope haulage roadway on the other side of the stope and digging a stope branch roadway at one side of the stope haulage roadway, while mining and filling the stope branch roadway and the two-winged adits at one side of the stope haulage roadway, wherein, the stope branch roadway is located between two adjacent stope branch roadway; and k. performing two-winged adits mining and filling in the stope branch roadway by repeating steps b, c, d, e, f, and g, until the coal resource in the entire stope has been mined out and filled.
 2. The method according to claim 1, wherein: an included angle α between the direction perpendicular to the stope branch roadway and the adit is determined according to a requirement of the working angle of the coal mining equipment.
 3. The method according to claim 1, wherein: a width of each two-winged adit is substantially equal to a working width of a coal mining equipment.
 4. The method according to claim 1, wherein: distance L between adjacent stope branch roadways at the same side of the stope haulage roadway is determined by the formula L≈L₁+2L₂ ^(cosα), where, L₁ is a width of a stope branch roadway, and L₂ is a length of an adit. 